The process by which plants convert sunlight into chemical energy which can later be used for their cellular functions is called photosynthesis.
This chemical energy is stored in the form of sugar.
Oxygen is the byproduct of the physio-chemical process.
It occurs when plants convert carbon dioxide and water present in the environment in the presence of Sunlight.
Leaves contain cellular organelles known as chloroplast which has a green-coloured pigment called chlorophyll.
Sunlight Is absorbed by this chlorophyll where are carbon dioxide and water enter through the tiny pores of stomata present in the epidermis of leaves.